1. Field of the Invention
This invention relates to the field of construction. More specifically, the invention comprises an illuminated warning panel intended to signify the presence of a sidewalk/roadway boundary to a pedestrian.
2. Description of the Related Art
The present invention is suitable for use as part of existing sidewalk/curb structures. A brief explanation of the prior art structures may therefore aid the reader's understanding. FIGS. 1-4 illustrate prior art structures. FIG. 1 shows a traditional sidewalk/curb interface intended to accommodate handicapped persons. Several decades ago, sidewalk 14 simply terminated at its intersection with curb 10. The sharp rise of the curb presented an obstacle to wheelchairs and to pedestrians unable to take a moderately high step.
The structure shown in FIG. 1 is typical of the first-generation solution to this problem. Curb ramp 16 cuts through curb 10 to connect side walk 14 to the road surface within defined crossing 12. The ramp surface allows a wheelchair to smoothly transition from the sidewalk to the roadway and vice versa.
While functional, the ramp shown in FIG. 1 does not adequately warn visually-impaired persons that they are approaching a roadway. To address this issue, “detectable warning panels” are now added to the lower portion of the ramp. FIG. 2 shows a modified ramp assembly. Two detectable warning panels 18 have been affixed to the ramp near the portion that intersects the roadway. These warning panels include a pattern of raised domes (small “bumps”). The domes may be felt through the shoes of a person walking. They also vibrate the wheels of a wheelchair sufficiently to alert the wheelchair's operator. They are sometimes referred to as “Braille for the feet.”
The panels are often also given a bright color—such as yellow. The coloring assists many people in recognizing the sidewalk/curb boundary. The combination of the pattern of raised domes and the bright coloring provides a positive indication of the boundary to able-bodied and disabled persons alike.
FIG. 3 provides plan and elevation views for a detectable warning panel that is currently in widespread use. This particular panel is molded of fiber-reinforced thermoplastic. Base 20 is secured in position on a concrete sidewalk using adhesives, threaded fasteners, or the like. The pattern of domes protrudes upward from the base as shown in the elevation view.
FIG. 4 is a sectional view through a portion of the molded panel. The reader will observe that the panel is molded as an integral unit. Base 20 includes bevel 26 along its perimeter. Each dome 22 includes a flat 24 across its upper extreme. The base of each dome has a diameter of approximately 1 inch (25 mm). The dome-to-dome spacing is typically between about 1.5 inches (38 mm) and about 2.5 inches (64 mm).
Returning to FIG. 2, the reader will observe that two detectable warning panels 18 have been used to span the width of the ramp. Many prior art panels may be cut, ground, or otherwise fitted to the installation space. Thus, it is known to use 2½ panels in some applications. Still other prior art panels are made in long lengths (12″×36″). In that case a single panel may be used to span the desired width.
One disadvantage of the prior art warning panels involves their use in low light. On a dark street, the detectable warning panel may not be readily visible. In some circumstances the presence of the warning panels and particularly the presence of the pattern of raised domes may even create a trip hazard in low light. The present invention seeks to retain the advantages of the prior art warning panels while addressing the concern of their use in low light.